The distribution of Fe-59 labelled uteroferrin in the uterine endometrium, placenta, allantoic and amniotic fluid and fetus will be studied to determine whether or not porcine uteroferrin serves as the primary means for transferring iron from dam to fetus. Also, rate of transfer into the conceptus and half-life of uteroferrin in allantoic fluid will be related to stage of gestation. Proteases and protease inhibitors which may affect events associated with implantation (placentation) will be evaluated with special attention given to plasminogen activator, collagenase and trypsin-like proteases. To better define the possible significance of high levels of fructose in the fetal fluids and plasma of fetal pigs, evidence for fructose production from the phosphogluconate pathway will be studied. Placental versus uterine endometrial metabolism of glucose to fructose, phosphohexose isomerase and glucose-6-phosphate dehydrogenase activities will be determined and related to endocrine status of the female. Equine and porcine uteroferrin will be compared with respect to enzymatic properties and physical characteristics and immunological similarities.